The objective of this research is to study and characterize the uptake of choline by the isolated, ventilated and perfused newborn lung and its incorporation into phosphatidylcholine. The uptake of perfusate 14C-choline and its incorporation into perfused viable newborn lung phosphatidylcholine (PC) and intermediates phosphorylcholine and CDP-choline will be studied. The incorporation will be characterized further by: (a) determining the effect of time of perfusion; (b) noting the effect of various concentrations of perfusate choline; (c) altering conditions of the perfusate (such as pH, glucose, calcium); (d) studying species similarities or differences between perfused newborn rabbit and pig lung; (e) noting any competition of ethanolamine with choline. PC synthesis and uptake of perfused 14C-choline into intermediates will be assessed after separation of intermediates and PC from other lipids using enzymes, thin layer, paper and gas-liquid chromatography.